Multiple coil system for tracking a medical device

ABSTRACT

A system for tracking the position of one or more medical devices for insertion into the body of a patient is disclosed. The system may also be used to locate one or medical devices at a later time after placement thereof. The present system employs multiple radiating elements that can be simultaneously detected by a sensor unit of the system, wherein at least one of the radiating elements is included with the medical device. Another of the radiating elements may be placed at a predetermined point on the skin of the patient to serve as a landmark to help determine the location of the medical device with respect to the landmark. Detection of the radiating elements by the sensor unit enables the relative positions of the radiating elements to be ascertained and depicted on a display, to assist a clinician in accurately positioning the medical device, such as a catheter.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 62/289,126, filed Jan. 29, 2016, and titled “MultipleCoil System for Tracking an Indwelling Medical Device,” which isincorporated herein by reference in its entirety.

BRIEF SUMMARY

Briefly summarized, embodiments of the present invention are directed toa system for tracking the position of one or more medical devices for atleast partial insertion into and/or advancement within the body of apatient. The system may also be used to locate one or medical devices ata later time after placement thereof.

The present system includes the use of multiple radiating elements thatcan be simultaneously detected by a sensor unit of the system, whereinat least one of the radiating elements is included with the medicaldevice, in one embodiment. Another of the radiating elements may beplaced at a predetermined point on the skin of the patient to serve as alandmark to help determine the location of the medical device withrespect to the landmark.

Detection of the radiating elements by the sensor unit enables therelative positions of the radiating elements to be ascertained anddepicted on a display, including two and/or three-dimensionaldepictions, so as to in turn enable a clinician to observe the relativeposition of the medical device(s) and landmarks. This assists theclinician in positioning the medical device in a desired position withinthe patient body.

In one embodiment, therefore, a system for tracking a medical devicewith respect to a body of a patient is disclosed, comprising a displayand a first radiating element. The first radiating element is includedwith the medical device and is capable of producing a firstelectromagnetic field. A second radiating element capable of producing asecond electromagnetic field is also disclosed and is positioned withrespect to the body of the patient. A sensor unit is operably connectedto the display, wherein the display is configured for depiction ofinformation relating to detection by the sensor unit of the first andsecond electromagnetic fields of the first and second radiatingelements.

These and other features of embodiments of the present invention willbecome more fully apparent from the following description and appendedclaims, or may be learned by the practice of embodiments of theinvention as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

A more particular description of the present disclosure will be renderedby reference to specific embodiments thereof that are illustrated in theappended drawings. It is appreciated that these drawings depict onlytypical embodiments of the invention and are therefore not to beconsidered limiting of its scope. Example embodiments of the inventionwill be described and explained with additional specificity and detailthrough the use of the accompanying drawings in which:

FIG. 1 is a block diagram depicting various elements of an integratedsystem for intravascular placement of a catheter or other medicaldevice, according to one example embodiment of the present invention;

FIG. 2 is a simplified view of a patient and a catheter being insertedtherein with assistance of the integrated system of FIG. 1;

FIGS. 3A and 3B depict various views of the sensor unit of the system ofFIG. 1;

FIG. 4 is a perspective view of an untethered stylet configured inaccordance with one embodiment;

FIG. 5 is a cross sectional view of a distal portion of the stylet ofFIG. 4;

FIG. 6 is a simplified block diagram of a control module portion of theuntethered stylet of FIG. 4, together with associated components of theconsole of FIG. 1;

FIGS. 7A and 7B are various views of a datum module according to oneembodiment;

FIG. 8 is a simplified block diagram of a control module portion of thedatum module of FIGS. 7A and 7B, together with associated components ofthe console of FIG. 1;

FIG. 9 is a simplified diagram showing various components employed insynchronizing a pulse signal frequency between a wireless stylet and aconsole of the system of FIG. 1;

FIG. 10 is a simplified view of a patient and a catheter being insertedtherein with assistance of the integrated system of FIG. 1;

FIG. 11 is a screenshot as depicted on a display of the integratedsystem of FIG. 1, indicating a position of a distal end of the stylet ofFIG. 4 during catheter tip placement procedures;

FIG. 12 is a simplified view of a patient and a catheter being insertedtherein with assistance of the integrated system of FIG. 1;

FIG. 13 is a screenshot as depicted on a display of the integratedsystem of FIG. 1, indicating a position of a distal end of multiplestylets such as that shown in FIG. 4 during catheter tip placementprocedures;

FIG. 14 is a side view of a stylet including multiple radiating elementsin accordance with one embodiment;

FIG. 15 is a partial cross sectional view of a vessel including aplurality of stylets positioned therein in accordance with oneembodiment;

FIG. 16 is a perspective view of a flexible sensor unit in accordancewith one embodiment;

FIG. 17 is a simplified view of the sensor unit of FIG. 16;

FIGS. 18A and 18B depict various views of a needle assembly according toone embodiment;

FIG. 19 is a perspective view of a distal portion of the needle assemblyof FIGS. 18A and 18B;

FIG. 20 shows the needle assembly of FIGS. 18A and 18B in use;

FIG. 21 is a perspective view of a breast marker in accordance with oneembodiment; and

FIG. 22 is a partial cross-sectional view showing an imaging operationfor breast markers such as those shown in FIG. 21.

DETAILED DESCRIPTION OF SELECTED EMBODIMENTS

Reference will now be made to figures wherein like structures will beprovided with like reference designations. It is understood that thedrawings are diagrammatic and schematic representations of exemplaryembodiments of the present invention, and are neither limiting nornecessarily drawn to scale.

For clarity it is to be understood that the word “proximal” refers to adirection relatively closer to a clinician using the device to bedescribed herein, while the word “distal” refers to a directionrelatively further from the clinician. For example, the end of acatheter placed within the body of a patient is considered a distal endof the catheter, while the catheter end remaining outside the body is aproximal end of the catheter. Also, the words “including,” “has,” and“having,” as used herein, including the claims, shall have the samemeaning as the word “comprising.”

Embodiments of the present invention are generally directed to a systemfor tracking the position of one or more medical devices for at leastpartial insertion into and/or advancement within the body of a patient.The system may also be used to locate one or medical devices at a latertime after placement thereof. Examples of medical devices that can betracked and positioned using the present system include catheters,breast markers, needles, etc.

The present system includes the use of multiple radiating elements thatcan be simultaneously detected by a sensor unit of the system, whereinat least one of the radiating elements is included with the medicaldevice, in one embodiment. Another of the radiating elements may beplaced at a predetermined point on the skin of the patient to serve as alandmark to help determine the location of the medical device withrespect to the landmark. Detection of the radiating elements by thesensor unit enables the relative positions of the radiating elements tobe ascertained and depicted on a display, including two and/orthree-dimensional depictions, so as to in turn enable a clinician toobserve the relative position of the medical device(s) and landmarks.This assists the clinician in positioning the medical device in adesired position within the patient body.

In one embodiment, for example, one of the radiating elements includesan electromagnetic coil that is included with a stylet. The stylet isremovably received within a lumen of a catheter that is introduced andadvanced through the vasculature of the patient. Another radiatingelement, such as a second electromagnetic coil, is placed atop the chestof the patient to serve as a reference point, or landmark. A sensor unitcan be placed in proximity to the patient, such as at the bedside of thepatient, so as to enable both electromagnetic coils to be detectedduring insertion and advancement of the catheter. Detection and trackingof the two electromagnetic coils can enable the clinician to determineif the catheter is being advanced along a desired route or if thecatheter has been malpositioned or has encountered an obstacle. In oneembodiment, data received from tracking the electromagnetic coils can beused to map the path of catheter advancement, which map can be depictedon a display for use by the clinician, or stored for future reference.Note that more than two coils can be included and used by the system toprovide additional data points for accurately detecting the position andadvancement of the medical device. Also, more than one medical devicecan be tracked by the system, in one embodiment.

FIGS. 1 and 2 depict various details of a medical device tracking system(“system” or “tracking system”), generally designated at 10, whichserves as one example environment wherein embodiments of the presentdisclosure can be practiced. The system 10 is employed to assist aclinician in the placement of a catheter or other medical device(s)within the body of a patient, such as within a vein or other vessel. Inone embodiment, the medical device includes a catheter and the intendeddestination of the catheter within a vein of the patient body is suchthat the distal tip of the catheter is disposed in the lower ⅓^(rd)portion of the superior vena cava (“SVC”). As such, the system assiststhe clinician by tracking and visualizing advancement of the catheter orother medical device(s) as it advances toward its intended destinationwithin the patient body.

As mentioned, FIGS. 1 and 2 depict various components of the system 10in accordance with one example embodiment. As shown, the system 10generally includes a console 20, display 30, and sensor unit (“sensor”)50, each of which is described in further detail below.

FIG. 2 shows the general relation of these components to a patient 70during a procedure to place a catheter 72 into the patient vasculaturethrough a skin insertion site 73. FIG. 2 shows that the catheter 72generally includes a proximal portion 74 that remains exterior to thepatient and a distal portion 76 that resides within the patientvasculature after placement is complete. In the present embodiment, thesystem 10 is employed to ultimately position a distal tip 76A of thecatheter 72 in a desired position within the patient vasculature. In oneembodiment, the desired position for the catheter distal tip 76A isproximate the patient's heart, such as in the lower one-third (⅓^(rd))portion of the Superior Vena Cava (“SVC”). Of course, the system 10 canbe employed to place the catheter distal tip in other locations. Thecatheter proximal portion 74 further includes a bifurcation hub 74A thatprovides fluid communication between the one or more lumens of thecatheter 72, one or more extension tubes 74B extending proximally fromthe hub, and corresponding connectors 74C for enabling connection to thecatheter 72.

FIG. 1 shows that a processor 22, including non-volatile memory such asEEPROM for instance, is included in the console 20 for controllingsystem function during operation of the system 10, thus acting as acontrol processor. A digital controller/analog interface 24 is alsoincluded with the console 20 and is in communication with both theprocessor 22 and other system components to govern interfacing betweenthe sensor 50, and other system components.

The system 10 further includes ports 52 for connection with the sensor50 and optional components 54 including a printer, storage media,keyboard, etc. The ports in one embodiment are USB ports, though otherport types or a combination of port types can be used for this and theother interfaces connections described herein. A power connection 56 isincluded with the console 20 to enable operable connection to anexternal power supply 58. An internal battery 60 can also be employed,either with or exclusive of an external power supply. Power managementcircuitry 59 is included with the digital controller/analog interface 24of the console to regulate power use and distribution.

The display 30 in the present embodiment is integrated into the console20 and is used to display information to the clinician during thecatheter placement procedure. In another embodiment, the display may beseparate from the console. In one embodiment, a console button interface32 can be used to control depiction of images on the display 30 by theclinician to assist in the placement procedure, as will be seen. In oneembodiment, the display 30 is an LCD device. Also, the buttons includedon the console button interface 32 can be configured in a variety ofways, including the use of user input controls in addition to buttons,such as slide switches, toggle switches, electronic or touch-sensitivepads, etc.

As mentioned, the system 10 is configured to detect and track aplurality of radiating elements associated with one or more medicaldevices for placement within the body of the patient. Thus, the system10 enables the clinician to quickly locate and confirm the positionand/or orientation of one or more medical devices, such as aperipherally-inserted central catheter (“PICC”), central venous catheter(“CVC”), or other suitable catheter or medical device, during initialplacement into and advancement through the vasculature or other bodyportion of the patient 70.

Briefly, the system 10 is configured to detect electromagneticradiation, such as an electromagnetic field, generated by a radiatingelement included with the medical device(s). In the embodiment shown inFIGS. 1 and 2, for instance, a radiating element (to be describedfurther below) is included proximate the distal tip 76A of the catheter72. The radiating element, together with one or more other radiatingelements, is detectable by the sensor unit 50 placed in proximity to thepatient, thus enabling the display 30 to graphically depict the detectedlocation of the radiating element, and thus the distal tip 76A of thecatheter 72. This assists the clinician to ascertain the generallocation and orientation of the catheter tip within the patient body. Itis appreciated that the teachings of one or more of the following U.S.patents may be employed in one embodiment in the above-describedtracking: U.S. Pat. Nos. 5,775,322; 5,879,297; 6,129,668; 6,216,028; and6,263,230. The contents of the afore-mentioned U.S. patents areincorporated herein by reference in their entireties. Note that thesystem 10 in one embodiment can display the direction in which thecatheter distal tip 76A is pointing, thus further assisting accuratecatheter placement. The system 10 in one embodiment can further assistthe clinician in determining when a malposition of the catheter tip hasoccurred, such as in the case where the catheter distal tip 76A hasdeviated from a desired venous path into another vein.

In accordance with one embodiment, the above-described radiating elementis included with a stylet that is removably inserted into the cathetersuch that the radiating element is co-terminal with the distal end ofthe catheter. Further, the stylet including the radiating element isphysically untethered to a console or other component of the system 10.Thus, the stylet itself includes all necessary componentry for producingthe electromagnetic field, such as an electrical pulse signal, for useby the system. The stylet in one embodiment further includesfunctionality to synchronize its pulsing activities with the console 20of the system 10 such that the system can accurately track advancementof the stylet and its corresponding catheter through the patientvasculature. In another embodiment, the stylet including the radiatingelement can be tethered to the sensor unit or other component of thesystem 10 in such a way as to enable the passage of driving signals fromthe sensor unit 50 or system console 20 to the radiating element througha sterile barrier interposed between the catheter/stylet and sensor unitor console without compromising the barrier itself or the sterile fieldit helps establish.

As mentioned, the system 10 in the present embodiment utilizes a styletto enable the distal end of the catheter 72 to be tracked during itsadvancement through the vasculature. FIGS. 4 and 5 give an example of adetached configuration of such a stylet 130, configured in accordancewith one embodiment. In particular, the stylet 130 in FIGS. 4 and 5 isphysically detached, or untethered, from other components of the system10. The stylet 130 includes a proximal end 130A and a distal end 130B. Acontrol module 102 for the stylet 130, also referred to herein as a“fob,” is included at the stylet proximal end 130A, with an elongateportion 134 extending distally therefrom.

FIG. 5 gives further details regarding a distal portion of the styletelongate portion 134 proximate the stylet distal end 130B. As shown andas mentioned above, the stylet 130 includes a first radiating element150, here embodied as an electromagnetic (“EM”) coil 106, which isincluded proximate the stylet distal end 130B and is operably connectedto leads 106A. The EM coil 106 and leads 106A can include insulatedcopper wire in the present embodiment. The leads 106A are in turnoperably connected to corresponding circuitry located in the styletcontrol module 132 configured to produce an electric pulse signal so asto enable the EM coil 106 to be electrically pulsed during operation andproduce an electromagnetic field having a predetermined frequency orpattern that is detectable by one or more sensors included in the sensorunit 50 during transit of the catheter 72 through the vasculature whenthe EM coil 106 is within the detectable range of the sensor unit.

Note that the EM coil 106 described herein is but one example of aradiating element, or a component capable of producing electromagneticradiation, such as an electromagnetic field for detection by the sensorunit. Indeed, other devices and assembly designs can be utilized here toproduce the same or similar functionality. For instance, non-limitingexamples of other stylet configurations can be found in U.S. Pat. No.9,901,714, filed Aug. 21, 2009, and entitled “Catheter AssemblyIncluding ECG Sensor and Magnetic Assemblies,” which is incorporatedherein by reference in its entirety. In the embodiments herein, morethan one radiating element is included for use with the system 10, aswill be described further below. In another embodiment, radiatingelements of different types (e.g., ultrasonic and electromagnetic) canbe included together.

The EM coil 106 and leads 106A are disposed within tubing 108 thatextends at least a portion of the length of the stylet elongate portion134. In one embodiment. The tubing includes polyamide. The EM coil 106and leads 106A can be protected in other ways as well. A core wire 110is also included within the tubing 108 in one embodiment to offerstiffness and/or directional torqueability to the stylet elongateportion 134. The core wire 110 in one embodiment includes nitinol andcan extend to the distal end 130B of the stylet 100 or terminateproximal thereto. In the present embodiment, at least the portion of thecore wire 110 that extends within the EM coil 106 includes aferromagnetic and/or magnetically permeable material, such as iron,iron-containing steel, or other suitable material. Note that the EM coilcan be configured in other ways as well; as such, the disclosure hereinregarding this and the other radiating elements is not intended to belimiting.

In accordance with the present embodiment, the stylet 130 is untethered,or physically unconnected, with respect to the console 20 of the system10. As such, the electric pulsing of the EM coil 106 to produce thepredetermined electromagnetic field is driven by suitable componentryincluded in the fob, or stylet control module 132, as opposed to pulsedriving by the console or other system component to which the styletwould be physically connected. FIG. 6 shows such componentry accordingto one example embodiment. The control module 132 includes a housing132A in which a printed circuit board (“PCB”) 232 or other suitableplatform is housed. Pulse circuitry 234 is disposed on the PCB 232 andincludes a timer circuit 236 configured to provide electrical pulses tothe EM coil assembly 106 via the leads 106A (FIG. 5). It is noted thatin one embodiment the electromagnetic field can be pulsed so as toproduce a predetermined pattern, if desired.

A connector 230A is included on the control module housing 132A andconfigured to removably and operably connect with a correspondingconnector 230B included on a proximal end of the stylet elongate portion134. In this way, operable connection between the timer circuit 236 andthe EM coil 106 via the leads 106A is achieved in the presentembodiment. Note that other connective schemes between the pulsecircuitry 234 and the EM coil 106 can be used. In another embodiment,the stylet elongate portion is permanently connected to the styletcontrol module.

A power supply 240 is included with the stylet control module 132 toprovide power necessary for control module functions, includingoperation of the pulse circuitry 234 and driving of the electric pulsingperformed by the timer circuit 236. In one embodiment, the stylet 130 isa disposable, one-time use component and as such the power supply 240 isalso disposable, such as a button-cell battery. In other embodiments,the power supply can be a rechargeable battery, a long-life powersupply, or can be configured to be replaceable as may be appreciated byone skilled in the art. In one embodiment, the stylet control module 132includes an on/off switch for controlling operation of the controlmodule components.

As mentioned, the timer circuit 236 drives the EM coil 106 by sendingelectrical pulses at a predetermined frequency to the EM coil via theleads 106A to which the timer circuit is operably connected. Receipt ofthe pulses causes the EM coil 106 to emit an electromagnetic fieldhaving the predetermined frequency that is detectable by the sensor unit50 of the system 10, thus assisting guidance of the catheter 72 (FIG. 2)as described herein.

In one embodiment, the electric pulse signal of the timer circuit 236 issynchronized with the console 20, or other system component (such as thesensor unit 50), to enable the system 10 to identify the frequency ofthe field produced by the EM coil 106 as a result of the pulsing. Thisenables the console 20 to identify the proper field relating to the EMcoil 106 of the stylet 130 and the sensor unit 50 to accurately trackprogress of the stylet during intravascular advancement of the catheter72. The particular frequency/frequencies employed for the pulse signalin one embodiment comply with applicable laws and regulations, includingregulations promulgated by the Federal Communications Commission(“FCC”). In one implementation a frequency of about 1 MHz may be used,for example.

In the present embodiment, synchronization of the pulse signal frequencyproduced by the timer circuit 236 with the console 20 is achieved by atransmitter 238 included with the stylet control module 132, as seen inFIGS. 4 and 6. The transmitter 238 is operably connected to and receivesdata from the timer circuit 236 relating to the frequency of its pulsesignal being sent to the EM coil 106. The transmitter 238 transmits thedata to a receiver 242 included on the console 20. Receiving the data bythe receiver 242, the console 20 can then identify the electromagneticfield produced by the EM coil 106 when detected by the sensor unit 50and thus track intravascular advancement of the catheter 72.

In one implementation, the data transmitted by the transmitter 238include a message detailing the pulsing frequency of the pulse signalproduced by the timer circuit 236. In another implementation, the dataare merely a replication of the pulse signal itself that, when receivedby the console 20, enable the console to determine the frequency. Theconsole processor 22 (FIG. 1) or other suitable console circuitry can beemployed to perform this determination functionality. Of course, thedata can take any one of a variety of formats and configurations toenable information relating to the pulse signal to be received by theconsole 20 or other suitable component of the system. In certainembodiments, the console 20, the sensor unit 50, or other suitablecomponent of the system 10 can include the necessary circuitry tosynchronize with the signal produced by the stylet 130, as describedherein.

The transmitter 238 can transmit, and the receiver 242 receive, theabove-referenced data in any number of ways, but in one implementationthe transmitter wirelessly transmits via infrared (“IR”) orradiofrequency (“RF”) radiation wavelengths for receipt by the receiver.As such, for example, the transmitter 238 and receiver 242 can beconfigured as an IR LED/detector pair in the first case, or as anantenna pair in the second case. Note that other types oftransmitter/receiver configurations can be included to perform theintended functionality described herein. Other forms of electromagneticradiation can be employed to transmit data, including visible light inone embodiment. Also note that the transmitter 238 and the receiver 242can each serve as transmitters/receivers in this and other embodimentsherein.

In one embodiment, the timer circuit of the untethered stylet controlmodule is configured to be adjustable such that the pulse frequency canbe selected from a plurality of predetermined frequency options. Suchfunctionality may assist in the case where interference exists on one ormore of the predetermined frequencies, where different stylets are usedsuccessively by the same system (as discussed below), or where multiplesystems are used simultaneously in close proximity to one another. Insuch a configuration, a selector switch may be included on the controlmodule housing 132A, the console 20, and/or other suitable systemcomponent. The above or other suitable synchronization scheme can beused to coordinate the selected pulse frequency to be transmitted andreceived between the stylet control module and the console.

In another implementation, the stylet control module/consoleautomatically switches to one of a plurality of possible pulsefrequencies for use in driving the EM coil. In this latterimplementation, the console can be configured to successively scan theplurality of possible frequencies and perform frequency identificationfunctions, including phase locking (e.g., via a phase locking circuit),to identify the frequency on which the stylet control module timercircuit is producing the electrical pulse signal, as well as thefrequencies of other EM coils of the system, thus enablingsynchronization of the console therewith.

FIG. 9 shows an example of the above automatic synchronizationimplementation, according to one embodiment. As shown, a transmittersuch as an antenna 239 is included with the stylet control module 132and is configured to emit radiofrequency (“RF”) or other suitablesignals. A receiver such as an antenna 243 is included with the console20 of the system 10 to receive signals emitted by the stylet controlmodule antenna 239. The console 20 further includes various componentsfor processing signals received by the antenna 243, including a mixer363, an oscillator 365, a low pass filter 364, an analog-to-digitalconverter (“ADC”) 367, and a digital signal processor (“DSP”) 368.

During operation of the system 10, the stylet antenna 239 of the styletcontrol module 132 emits an RF or other suitable signal (e.g., infrared(“IR”)) that provides data relating to the frequency of the pulsesignal. The RF signal is received by the console antenna 242. The mixer363 combines the signal received by the antenna 242 with a predeterminedsignal generated by the oscillator 365, which combined signal is thenfiltered through the low pass filter 364 to remove any extraneoussignals. The filtered and combined signal is passed through the ADC 367,then analyzed by the DSP 368 to determine whether the two signalsforming the combined signal match. If so, phase shifting of the signalswill be performed by the DSP and/or oscillator 365 to lock the signalsin phase.

If the signals do not match, the above process is repeated with a newsignal having a different frequency being produced by the oscillator365. The above process is iteratively repeated until the signal from theoscillator 365 matches in frequency the signal emitted by the styletcontrol module antenna 239 and subsequently received by the consoleantenna 242. Thus, the oscillator 365 in one embodiment is capable ofcycling through a plurality of pre-set signal frequencies in attemptingto match the emitted signal of the stylet control module antenna 239. Inanother embodiment, the oscillator can cycle through a range offrequencies in attempting to match the emitted signal. As noted before,once the proper signal frequency is determined by the console 20, phaseshifting as needed can be conducted to complete synchronization betweenthe EM coil 106 of the stylet 130 and the console 20, thus enabling theconsole to track the EM coil.

It is understood that the above is merely one example of synchronizingthe pulse signal produced by the stylet coil assembly with the consoleand that other implementations can be employed to link the frequencybetween the stylet coil assembly and console or other component of thesystem.

In another embodiment, it is appreciated that the transmitter/receiverconfiguration can be reversed such that the transmitter is included withthe console and directs information regarding the frequency of the pulsesignal to the stylet control module, which receives the information viaa receiver included therein. In yet another embodiment, both the styletand the console are manufactured to operate with a pre-set pulse signalfrequency, requiring no subsequent synchronization therebetween. Theseand other possible configurations are therefore contemplated. Generally,it should be understood that the pulse circuitry and timer circuit ofthe stylet control module, together with the processor of the console20, can be configured in one or more of a variety of ways to achieveabove-described functionality. For instance, the processor 22 of theconsole 20 can be included in the sensor unit 50 (FIGS. 1, 3) such thatsynchronization operations on behalf of the system 10 are performed bythe sensor unit. Or, in another embodiment the stylet functionality isincorporated into the catheter itself and no removable stylet isemployed.

As mentioned, the system 10 in the present embodiment utilizes multipleradiating elements to assist in tracking a medical device(s) as it isinserted into a patient body and/or to locate the medical devicepost-insertion. As discussed above the radiating element 150,implemented as the EM coil 106 included in the catheter stylet 130,serves as the first radiating element to provide an electromagneticfield that can be tracked by the system 10. FIGS. 7A and 7B show a datummodule 158 that houses a second radiating element 160, implemented inthe present embodiment as an electromagnetic (“EM”) coil 276 configuredto an electromagnetic field detectable by the sensor unit 50 of thesystem 10, similar to the detection of the EM coil 106 of the stylet130, and depicted graphically on the display 30 of the system 10. In thepresent embodiment, the datum module 158 is employed to serve as areference point or external landmark (e.g., external marker) to assistin determining the location of the EM coil 106 of the stylet 130 as thecatheter 72 is advanced through the vasculature of the patient. As such,in the present embodiment the datum module 158 can be placed on a skinsurface of the patient 70 and, when detected by the sensor unit 50 canhelp determine the location of the EM coil 106 of the catheter stylet bydepicting on the display 30 a positional relationship between the EMcoil 106 and the EM coil 276 of the datum module 158, which itself islocated at a landmark on the patient skin surface.

FIGS. 7A and 7B depict various details of the datum module 158, inaccordance with the present embodiment. As shown, the datum module 158includes an outer housing 250 that houses various components such asthose shown in simplified form in FIG. 7B, including a PCB 262 and apower source 270, such as a battery. Also shown in the housing 250 isthe second radiating element 160 referred to above, here implemented asthe EM coil 276, though it is appreciated that type of other radiatingelements can also be employed here, as is the case with the otherradiating elements referred to herein. The EM coil 276 is operablyconnected to the power source 270 via insulted copper wire leads or thelike to enable the EM coil to emit electric pulse signals during systemoperation. As is the case with the stylet 130 and its EM coil 106, thedatum module 158 and its EM coil 276 are physically detached, oruntethered, from other components of the system 10. The datum modulehousing 250 includes various other components for controlling operationof the datum module 158 and its interaction with the system 10 intracking medical devices.

The datum module 158 is configured to produce an electric pulse signalvia its EM coil 276 such that the resultant electromagnetic field havinga predetermined frequency or pattern is detectable by the sensorsincluded in the sensor unit 50. As mentioned, detection of the datummodule 158 by the sensor unit 50 enables it to serve as a referencepoint/landmark during transit of the catheter 72 and its correspondingEM coil-equipped stylet 130 through the vasculature.

FIG. 8 depicts the various components included in the datum module 158to enable it to operate as an untethered component as described hereinin accordance with the present embodiment, namely, the electric pulsingof the EM coil 276 to produce the predetermined electromagnetic field.The components include a printed circuit board (“PCB”) 262 or othersuitable platform, pulse circuitry 264 disposed on the PCB, and a timercircuit 266 configured to provide electrical pulses to the EM coil 276.It is noted that in one embodiment the electromagnetic field can bepulsed so as to produce a predetermined pattern, if desired.

A power supply 270 is included with the stylet control module 132 toprovide power necessary for control module functions, includingoperation of the pulse circuitry 264 and driving of the electric pulsingperformed by the timer circuit 266. In one embodiment, the datum module158 is a disposable, one-time use component and as such the power supply270 is also disposable, such as a button-cell battery. In otherembodiments, the power supply can be a rechargeable battery, a long-lifepower supply, or can be configured to be replaceable as may beappreciated by one skilled in the art. In one embodiment, the datummodule 158 includes an on/off switch for controlling its operation.

As with the EM coil 106 of the stylet 130, the timer circuit 266 of thedatum module 158 drives the EM coil 276 by sending electrical pulses ata predetermined frequency to the EM coil to which the timer circuit isoperably connected. Receipt of the pulses causes the EM coil 276 to emitan electromagnetic field having the predetermined frequency that isdetectable by the sensor unit 50 of the system 10, as described herein.

In one embodiment, the electric pulse signal of the timer circuit 266 issynchronized with the console 20, or other system component (such as thesensor unit 50), to enable the system 10 to identify the frequency ofthe field produced by the datum module EM coil 276 as a result of thepulsing. This enables the console 20 to identify the proper fieldrelating to the EM coil 276 of the datum module 158 and to differentiateit from the electromagnetic fields of other radiating elements of thesystem 10, such as the EM coil 106 of the stylet 130, discussed above.This in turn enables the sensor unit 50 and system 10 to accuratelytrack progress of the stylet 130 during intravascular advancement of thecatheter 72 as well as track the position of the datum module 158 as areference point to assist in localizing the position of the stylet (orother medical device) with respect to the datum module. As before, theparticular frequency/frequencies employed for the pulse signal in oneembodiment comply with applicable laws and regulations, includingregulations promulgated by the Federal Communications Commission(“FCC”).

In the present embodiment, synchronization of the pulse signal frequencyproduced by the timer circuit 266 with the console 20 is achieved by atransmitter 268 included with the datum module 158, as seen in FIG. 8.The transmitter 268 is operably connected to and receives data from thetimer circuit 266 relating to the frequency of its pulse signal beingsent to the EM coil 276. The transmitter 268 transmits the data to thereceiver 242 included on the console 20. Receiving the data by thereceiver 242, the console 20 can then identify the electromagnetic fieldproduced by the datum module EM coil 276 when detected by the sensorunit 50, differentiate it from the signals of any other EM coils of thesystem 10, and thus track both the intravascular advancement of thecatheter 72 and the position of the datum module 158. The configurationand operation of the transmitter 268 and the receiver 242 is similar tothat described in connection with the transmitter 238 and receiver 242with respect to the stylet control module 132, further above. Indeed,operation of the components of the datum module 158 shown in FIG. 8 issimilar to that described in connection with the components of thestylet control module 132 of FIG. 6. Further, the discussion relating toan automatic synchronization of pulse signal frequency between thestylet control module 132 and the console 20 detailed above inconnection with FIG. 9 also corresponds to synchronization of the datummodule 158 with the console, in the present embodiment, with the antenna239 representative of an antenna included with the datum module 158. Inanother embodiment, it is appreciated that the pulse signals of the EMcoils of the system can be multiplexed together (such as via time-basedmultiplexing), instead of differing in frequency/wavelength. As such,this and other modes for distinguishing the pulse signals of the variousradiating elements are appreciated.

As seen in FIGS. 3A and 3B and as mentioned above, the system 10includes a sensor unit 50 for detecting the position and movement of thefirst and second radiating element, i.e., the EM coil 106 of the stylet130 and the EM coil 276 of datum module 158 in the present embodiment,during a procedure to place or locate a medical device within the bodyof a patient. The sensor unit 50 includes a sensor array 190 comprisinga plurality of sensors 192 embedded within the housing of the sensorunit. The sensors 192 are configured to detect a magnetic field (asegment of its electromagnetic field) produced by the EM coils 106, 276,as well as any other radiating elements that are part of the system 10,such as in the case of multiple EM coils used to track a plurality ofmedical devices. Though they are shown in FIGS. 3A and 3B as includedwith the sensor unit 50 having a certain size and shape, the sensors 192of the sensor array 190 can be included in a sensor unit having adifferent shape, size, or other configuration. In the presentembodiment, the sensors 192 are disposed in a planar configuration belowa top face of the sensor unit 50, though it is appreciated that thesensors can be arranged in other configurations, such as in an arched orsemi-circular arrangement.

In the present embodiment, each of the sensors 192 includes threeorthogonal sensor coils for enabling detection of a magnetic field inthree spatial dimensions. Such three dimensional (“3-D”) magneticsensors can be purchased, for example, from Honeywell Sensing andControl of Morristown, N.J. Further, the sensors 192 of the presentembodiment are configured as Hall-effect sensors, though other types ofmagnetic sensors could be employed. Further, instead of 3-D sensors, aplurality of one dimensional magnetic sensors can be included andarranged as desired to achieve 1-, 2-, or 3-D detection capability.

In the present embodiment, six sensors 1192 are shown included in thesensor array 190 so as to enable detection of the EM coils 106, 276 innot only the three spatial dimensions (i.e., X, Y, Z coordinate space),but also the pitch and yaw orientation of the EM coil itself. Note thatin one embodiment, orthogonal sensing components of two or more of thesensors 192 enable the pitch and yaw attitude of the EM coil 106 forinstance, and thus the medical device, to be determined.

In other embodiments, fewer or more sensors can be employed in thesensor array. More generally, it is appreciated that the number, size,type, and placement of the sensors of the sensor array can vary fromwhat is explicitly shown here. In one embodiment, at least three sensorsare employed.

The placement of the sensor unit 50 can be varied according to type ofmedical device placement scenario, the logistics of the insertionprocedure, etc. For instance, FIG. 2 shows the sensor unit 50 positionedat a side of the patient 70 where it can detect the electromagneticfields produced by the EM coils 106, 276. Such a placement may be usedto position the sensor unit 50 at the bedside of the patient 70 in ahospital or clinic setting, for instance. However, multiple otherplacements of the sensor unit 50 are possible, including on the chest orother skin surface of the patient, adjacent a body part of interest,etc. Note further that the size, shape, and other configuration of thesensor unit can vary from what is explicitly shown and described herein.

Reference is made to FIGS. 2 and 10, which depict disposal of theuntethered stylet 130 substantially within a lumen in the catheter 72such that the proximal portion thereof, including the control module132, extends proximally beyond the catheter lumen, the hub 74A and aselected one of the extension legs 74B. So disposed within a lumen ofthe catheter, the first radiating element 150, implemented as the EMcoil 106 and located proximate the distal end 130B of the stylet 130, issubstantially co-terminal with the distal catheter end 76A such thatdetection by the system 10 of the stylet EM coil correspondinglyindicates the location of the catheter distal end. Further, the datummodule 158, including the second radiating element 160 implemented asthe EM coil 276, is also shown sitting atop a central portion of thechest of the patient 70, though it is appreciated that this is just oneof a variety of possible placement locations for the datum module, bothon or off the patient body, to serve as a reference marker. It isappreciated that both EM coils 106, 276 are powered and operating duringthe procedure so as to produce their respective electromagnetic fieldsfor detection.

Note that the electromagnetic field of each EM coil includes a uniquecharacteristic unique within the system 10 so as to be distinguishableand separately trackable by the system. This is accomplished in oneembodiment by each EM coil producing an electromagnetic field thatdiffers in frequency and/or amplitude from the other EM coil(s) of thesystem. Such differentiation of electromagnetic fields can be configuredas a permanent configuration for each EM coil at the time ofmanufacture/setup of the system 10, in one embodiment. In anotherembodiment, the system can actively assign and/or change the EM coilconfigurations using the teachings discussed above in connection withFIG. 9. Of course and more generally, other modes of producing uniquetypes of electromagnetic radiation from each radiating element are alsocontemplated herein. In one embodiment, the electromagnetic fields ofthe EM coils are time multiplexed together or treated to othermultiplexing operations. Thus, this is another example of a uniquecharacteristic the radiating elements can possess in order to bedifferentiated by the system.

The sensor unit 50 is employed by the system 10 during operation todetect the electromagnetic field produced by the EM coil 106 of thestylet 130. As mentioned above, the sensor unit 50 is placed in thepresent embodiment to the side of the patient 70 during catheterinsertion, one of a plurality of possible locations for the sensor unitto reside, to enable the field of the EM coil 106, disposed in thecatheter 72 as described above, to be detected during catheter transitthrough the patient vasculature. Again, as the EM coil 106 issubstantially co-terminal with the distal end 76A of the catheter 72(FIG. 2), detection by the sensor unit 50 of the field produced by theEM coil 106 provides information to the clinician as to the position andorientation of the catheter distal end 76A during its transit.

FIGS. 2 and 10 further depict the datum module 158 positioned on acentral chest portion of the patient 70. So disposed, the secondradiating element 160, implemented here as the EM coil 276, is preparedfor detection by the sensor unit 50 and to serve as a reference marker.

In greater detail, the sensor unit 50 is operably connected to theconsole 20 of the system 10 via the console cable 140 and one or more ofthe ports 52, as shown in FIGS. 1 and 2. Note that other connectionschemes between the sensor unit 50 and the system console 20 can also beused without limitation. As just described, the EM coil 106 is employedin the stylet 130 to enable the position of the catheter distal end 76A(FIG. 2) to be observable relative to the sensor unit 50 placed to theside of the patient. Detection by the sensor unit 50 of the stylet EMcoil 106 is graphically displayed on the display 30 of the console 20during system operation, represented in FIG. 11 (discussed below), forexample. In this way, a clinician placing the catheter 72 is able togenerally determine the location of the catheter distal end 76A withinthe patient vasculature relative to the sensor unit 50 and detect whencatheter malposition, such as advancement of the catheter along anundesired vein, is occurring.

Correspondingly, the EM coil 276 of the datum module 158 is employed toserve as a reference point for assisting location of the EM coil 106associated with the catheter (or other medical device). Detection by thesensor unit 50 of the datum module EM coil 276 can be graphicallydisplayed on the display 30 of the console 20 during system operation.This is shown in FIG. 11, which depicts a screenshot 380 of the display30 during operation of the system 10. As shown, the screenshot 380depicts a simplified stock outline body image 382. Also shown is an icon390 that represents the EM coil 106 disposed at the distal end of thestylet 130 and disposed in one of the lumens of the catheter 72 as it isbeing inserted through a vein of the patient 70 (FIG. 2). The icon 390shows the position of the EM coil 106 as detected by the sensor unit 50of the system 10. Also shown in broken line trailing the icon 390 is theprevious path of the EM coil 106 as it traversed through the vein.

FIG. 11 further shows an icon 394 that represents the EM coil 276 of thedatum module 158 that is positioned atop a central chest portion of thepatient 70, as shown in FIG. 2. The icon 394 shows the position of theEM coil 106 as detected by the sensor unit 50. As the datum module 158is kept relatively stationary during the catheter insertion procedure,the icon 394 stays relatively in place as depicted on the screenshot 380of the display 30. FIG. 10 shows that the system 10, by virtue of theability of the sensors 192 of the sensor unit 50 to detect the relativepositions of both EM coils 106 and 276, can determine (among otherpositional relationships) a distance z between the EM coil 106 and theEM coil 276 in real-time, thus determining a distance in the z-directionexisting between the distal 76A of the catheter 72 disposed within thevein and the skin surface of the central chest of the patient 70 wherethe datum module 158 is disposed. In this way, the datum module 158,with its EM coil 276, serves as a reference marker to further assist indetermining the location of the catheter 72 (or other medical device)with respect to a landmark, such as the chest of the patient 70.

Note that the icon 390 shown in FIG. 11 includes a central dotsurrounded by a varying number of concentric circles, wherein morecircles indicate a relatively deeper depth of the EM coil 106 asdetected by the sensor unit 50. The icon 394 representing the datummodule 158 includes a dot surrounded by a diamond. Of course, it isappreciated that a variety of other shapes and configurations can beemployed for the icons 390, 394. Note further that various depictionmodes can be depicted by the display in one embodiment, includetwo-dimensional and three-dimensional representations. Also, it isappreciated that the tracking of one or more radiating elements asdescribed herein can enable a clinician in one embodiment to map aportion of a vasculature or other structure of the patient, as well asidentify medical device mal-positions, obstacles/obstructions toadvancing the medical device, arterial vs. venous catheter placements,IVC vs. SVC device placement, innominate vein/artery placement, etc. Thesystem may be used in one embodiment for delicate medical deviceplacement, including neo-natal placements, placements where the patientis wearing a neck brace or other obstruction that would otherwise makemedical device placement difficult, etc.

It should be appreciated that in one embodiment the positions of theradiating element and the sensor can be reversed such that a remotelypowered sensor is included with the stylet and with the datum module fordetecting a field produced by a radiating element positioned external tothe body of the patient.

FIG. 12 depicts a system configuration according to another embodimentwherein the catheter 72, including the EM coil-equipped stylet 130, isinserted into a femoral vein at an insertion site 73 on an upper leg ofthe patient 70. The datum module 158 including its EM coil 276 ispositioned on a lower torso portion of the patient 70. The sensor unit50 is positioned to the side of the patient 70. The embodiment of FIG.12 depicts one of many possible implementations for the system 10,including insertion of a catheter through a lower portion of the patientbody, for instance. As such, it should be appreciated that a variety ofdifferent catheters can be placed by the system 10 as described herein,including urinary, ablation, arterial, PICC, CVC, etc.

FIG. 13 depicts a system configuration according to another embodiment,showing the screenshot 380 with the stock body image 382 superimposedthereon. Two icons 390 are shown, representing EM coils included onstylets that are disposed in two separate catheters that are beinginserted into different locations within the body of the patient. Inaddition, two icons 394 are shown, representing two EM soil-equippeddatum modules 158 that are disposed at different locations on the chestof the patient, such as bordering the perimeter of the heart, forinstance. Thus, this embodiment demonstrates the ability of the system10 to track more than two radiating elements, such as EM coils, in orderto assist in the placement of two or more medical devicessimultaneously. It should be appreciated that a variety of differentcombinations of radiating elements associated with datum modules andmedical devices may be employed by the system 10. For instance, in oneembodiment, four EM coils or other type of suitable radiating elementscan each be included with three datum modules and one medical device,for instance, in order to track the medical device to an intendeddestination within the patient body. These and other configurations aretherefore contemplated.

Note that, in one embodiment, the control module housing 132A of thestylet 130 can serve as a handle to assist in manipulating the catheter72 and/or stylet during intravascular advancement. Note also that theuntethered nature of the stylet 130 and the datum module 158 enabletheir use in a sterile setting without need to pierce a sterile barrierestablished around the patient during the medical device insertionprocedure with wires or other connection modes. However, in anotherembodiment, it is appreciated that the EM coils can be operated via wireattachment if desired.

It should appreciated herein that “stylet” as used herein can includeany one of a variety of devices configured for removable placementwithin a lumen of the catheter to assist in placing a distal end of thecatheter in a desired location within the patient's vasculature. In oneembodiment, the stylet includes a guidewire. As such, it is appreciatedthat stylets of other forms and configurations can also be acceptablyused, in accordance with the present disclosure.

FIG. 14 depicts a system configuration according to another embodiment,wherein the stylet 130 includes dual radiating elements, i.e., a firstradiating element 150 disposed proximate the distal end of the styletand an additional radiating element 162 disposed proximal to the firstradiating element. Thus, it is appreciated that the distribution as wellas the number of radiating elements can vary.

FIG. 15 depicts a system configuration according to another embodiment,wherein first and second stylets 130, 131 are disposed within a vessel406, such as a vein. In one embodiment, the first stylet 130 is guidedby a clinician to one of multiple stenoses 404 present in the vessel406, at which point further advancement is ceased. The second stylet 131can then be introduced into the vessel 406 and guided by the system 10to another of the stenoses 404, where further advancement is thenceased. The location of the stenoses can be confirmed and noted usingthe location ability of the system 10, wherein remedial procedures canbe undertaken to remove the stenoses 404.

FIGS. 16 and 17 depict details of the sensor unit 50 according toanother embodiment, including a flexible body, or flexible sheet 410,wherein a plurality of sensors 192 is disposed in a spaced-apartarrangement. Such a flexible sensor unit 50 can enable sensor placementon areas of the patient body, for instance, where curvature or bodyfeatures would otherwise make sensor unit placement difficult.

FIG. 17 shows that, in the present embodiment, each sensor 192 disposedwithin the flexible sheet 410 has positioned adjacent to it an EM coil414. So configured, the sensor unit 50 can be shaped as desired beforeoperation of the system 10 is commenced. For instance, the flexiblesheet 410 can be bent around a thigh of the patient. Then, the EM coils414 of each sensor 192 can be activated so that the system 10 candetermine the positional relationship of the sensors via a calibrationoperation. Thereafter, the sensor unit 50 is ready to be used indetecting EM coils, such as the EM coils 106, 276 described furtherabove. Should the flexible sensor unit 50 be moved or readjusted inplacement, another calibration of the sensors 192 would be performedbefore resuming system operations.

FIGS. 18A, 18B, and 19 depict details regarding another example of amedical device that can be used with the system 10, in accordance withone embodiment. As shown, a needle assembly 1200 is shown, including ahub 1304 from which extends a hollow cannula 1202. A needle safetycomponent 1320 is included is disposed on a distal end of the hub 1304.A control module 1314 is shown attached to a proximal end of the hub1304. A hole 1312 is shown defined through the control module 1314 andhub 1304.

A stylet 1390 extends from the control module 1314 and distally throughthe hub 1304 via the hole 1312 to extend into the lumen defined by thecannula 1202. A radiating element 1350, such as an EM coil 1392, isdisposed proximate a distal end of the stylet 1390. The control module1314 can include threads so as to threadably engage the needle hub 1304or other suitable component of the needle or medical component. In thisway, the stylet 1390 and associated EM coil 1392 is removably attachableto the needle 1200. Thus, the radiating element 1350 need not bepermanently affixed or included with the needle 1200, but rather can beremoved therefrom when EM coil-based needle guidance is no longerneeded. In addition, this enables the stylet 1390 and control module1314 to be attached to many different types and sizes of needles. Notethat in the present embodiment the distally slidable needle safetycomponent 1320 is configured to safely isolate the distal tip of theneedle 1200 upon removal of the needle from the patient.

The EM coil 1392 of the stylet 1390 as shown here enables the distal tipof the needle 1200 to be tracked and located when it is inserted into apatient in a manner similar to what has been described in previousembodiments, and as depicted in FIG. 20. As shown in FIG. 20, the distalportion of the needle cannula 1202 is shown inserted into the body ofthe patient. The stylet 1390 is inserted into the cannula 1202 such thatthe EM coil 1392 is disposed proximate the distal end of the cannula.Additionally, the datum module 158, including its own EM coil 276 (FIGS.7B, 8), is disposed on a skin surface above the subcutaneous needlecannula 1202. In this configuration, the system 10 is able to track anddepict on the display 30 the locations of the EM coils 276, 1392 of thedatum module 158 and the needle stylet 1390, respectively, using thedetection thereof by the sensor unit 50. This in turn enables theclinician to accurately guide the distal end of the needle cannula 1202to a desired location within the patient body. Thus, the presentembodiment of FIGS. 18A-19 serves as one of many examples of medicaldevices that can be tacked and guided by the present system 10.

FIGS. 21 and 22 depict details regarding another example of a medicaldevice that can be used with the system 10, in accordance with oneembodiment. As shown, a marker device, such as a breast marker 1400,includes in the present embodiment a radiating element 1450. Theradiating element 1450 in the present embodiment is a reactive orresonating type of EM coil, which resonates electromagnetically wheninduced by an external field provided by a suitable power source. Asshown in FIG. 22, in one example implementation multiple breast markers1400 are disposed in breast tissue 1460 of a patient, wherein eachbreast markers includes a resonating-type radiating element 1450. Thedatum module 158, including its EM coil 276, is placed on a skin surfaceof the breast. The sensor unit 50 can be placed in proximity to thebreast to enable the location of the breast markers 1400 and the datummodule 158 to be detected and located by the system 10, thus enablingthe clinician to determine the location of the breast markers at somepoint in time after initial implantation of the breast markers. Notethat in one embodiment the sensor unit 50 includes a suitable powersource to produce the responsive electromagnetic fields in theresonating-type radiating elements 1450 of the breast markers 1400.Thus, this serves as yet another example of a medical device that canbenefit from the tracking and location ability of the system 10.

Note that further details regarding untethered stylets and trackingsystems can be found in U.S. Pat. No. 9,526,440, filed Jun. 19, 2014,and entitled “System for Placement of a Catheter Including aSignal-Generating Stylet,” which is incorporated herein by reference inits entirety. Note further that other guidance modalities can beincluded with the system 10, including permanent magnet-based tracking,ultrasound imaging, and ECG-related guidance.

Embodiments of the invention may be embodied in other specific formswithout departing from the spirit of the present disclosure. Thedescribed embodiments are to be considered in all respects only asillustrative, not restrictive. The scope of the embodiments is,therefore, indicated by the appended claims rather than by the foregoingdescription. All changes that come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

What is claimed is:
 1. A system for tracking a catheter in a body of a patient, comprising: a display; a stylet designed for insertion through a lumen of the catheter, the stylet comprising: a stylet control module at a proximal end of the stylet, the stylet control module including a first power source and a first timer circuit, the first timer circuit designed to send an electrical pulse signal at a first predetermined frequency to a distal end of the stylet; and a first radiating element at the distal end of the stylet, the first radiating element designed to emit a first electromagnetic field with the first predetermined frequency; a datum module, comprising: a housing; a second power source and a second timer circuit enclosed by the housing, the second timer circuit designed to send an electrical pulse signal at a second predetermined frequency; and a second radiating element connected to the second timer circuit in the housing, the second radiating element designed to emit a second electromagnetic field with the second predetermined frequency; and a sensor unit operably connected to the display, the sensor unit designed to detect the first electromagnetic field in at least three spatial dimensions and to detect a position of the second radiating element with respect to the first radiating element, the display configured for depiction of information relating to detection by the sensor unit of the first electromagnetic field and the second electromagnetic field.
 2. The system as defined in claim 1, wherein the sensor unit includes an array of six sensors.
 3. The system as defined in claim 2, wherein the display is included in a console and wherein the sensor unit is operably connected to the console.
 4. The system as defined in claim 1, wherein the sensor unit is movable and is configured for placement on a portion of the body of the patient.
 5. The system as defined in claim 1, wherein the stylet control module and the datum module wirelessly communicate with the sensor unit.
 6. The system as defined in claim 3, wherein the first predetermined frequency is different from the second predetermined frequency.
 7. The system as defined in claim 6, wherein the first electromagnetic field and the second electromagnetic field are time multiplexed together.
 8. The system as defined in claim 6, wherein the first predetermined frequency and the second predetermined frequency can be changed via communication between the console, the stylet control module, and the datum module.
 9. The system as defined in claim 8, wherein the stylet control module and the datum module communicate with the console via either infrared or radiofrequency radiation wavelengths.
 10. The system as defined in claim 9, wherein each of the stylet control module and the datum module includes a transmitter to transmit data relating to the first timer circuit and the second timer circuit, respectively, to the console.
 11. The system as defined in claim 1, wherein the stylet control module is configured as a handle to assist in manipulating the catheter.
 12. The system as defined in claim 1, wherein the first radiating element includes a first electromagnetic coil, and wherein the second radiating element includes a second electromagnetic coil.
 13. The system as defined in claim 12, wherein the stylet includes an additional electromagnetic coil positioned at the distal end of the stylet proximal to the first electromagnetic coil.
 14. The system as defined in claim 1, wherein the datum module is designed to be placed proximate an external landmark of the body of the patient body.
 15. The system as defined in claim 14, wherein a detected position of each of the first radiating element and the second radiating element is depicted on the display, and wherein the display further depicts a representation of a portion of the body of the patient.
 16. The system as defined in claim 15, wherein the detected position of each of the first radiating element and the second radiating element is depicted on the display by a first icon and a second icon, respectively.
 17. The system as defined in claim 1, wherein the sensor unit is in the form of a flexible sheet, wherein a plurality of sensors is disposed in a spaced apart arrangement within the flexible sheet.
 18. The system as defined in claim 17, wherein an electromagnetic coil is positioned adjacent each of the plurality of sensors in the flexible sheet.
 19. The system as defined in claim 1, further comprising a third radiating element positioned at a distal end of a second stylet, the second stylet comprising a second stylet control module connected to the third radiating element. 